Rack-and-pinion steering is quickly becoming the most common type
of steering on cars, small trucks and SUVs. It is actually a pretty
simple mechanism. A rack-and-pinion gearset is enclosed in a metal
tube, with each end of the rack protruding from the tube. A rod,
called a tie rod, connects to each end of the rack.

The pinion gear is attached to the steering shaft. When you turn
the steering wheel, the gear spins, moving the rack. The tie rod at
each end of the rack connects to the steering arm on the spindle
(see diagram above).